ArticleThe Journal of general physiology2024
Calcium has a direct effect on thick filament activation in porcine myocardium.
Article in The Journal of general physiology, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers.
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Who cites it
8 citing papers in PubMed.
- Contractility Drives Cardiomyocyte Maturation and the Response to Nanopatterns.Circulation research · 2026Article
- The E525K β-Myosin Mutation Causes Hypocontractility in Cardiomyocytes Without Altering Loaded Crossbridge Cycling.bioRxiv : the preprint server for biology · 2026Article
- Porcine Left Atrial and Ventricular Thick Filaments Exhibit Distinct Resting Structures and Calcium-dependent Responses.bioRxiv : the preprint server for biology · 2026Article
- A primer on the methods of skeletal and cardiac muscle mechanics using permeabilized preparations.The Journal of general physiology · 2026Review
- ATP directly modulates thick filament structure and function in porcine myocardium.Biophysical journal · 2025Article
- Popping the hood of muscle motors using time-resolved, small-angle X-ray diffraction.Proceedings of the National Academy of Sciences of the United States of America · 2025Article
- Myosin-actin crossbridge independent sarcomere length induced CaJournal of molecular and cellular cardiology · 2025Article
- Thick-Filament-Based Regulation and the Determinants of Force Generation.Biomedicines · 2025Article
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Authors and funding
12 authors.
Funding
Abstract
Sarcomere activation in striated muscle requires both thin filament-based and thick filament-based activation mechanisms. Recent studies have shown that myosin heads on the thick filaments undergo OFF to ON structural transitions in response to calcium (Ca2+) in permeabilized porcine myocardium in the presence of a small molecule inhibitor that eliminated active force. The changes in X-ray diffraction signatures of OFF to ON transitions were interpreted as Ca2+ acting to activate the thick filaments. Alternatively, Ca2+ binding to troponin could initiate a Ca2+-dependent crosstalk from the thin filament to the thick filament via interfilament connections such as the myosin binding protein-C. Here, we exchanged native troponin in permeabilized porcine myocardium for troponin containing the cTnC D65A mutation, which disallows the activation of troponin through Ca2+ binding to determine if Ca2+-dependent thick filament activation persists in the absence of thin filament activation. After the exchange protocol, over 95% of the Ca2+-activated force was eliminated. Equatorial intensity ratio increased significantly in both WT and D65A exchanged myocardium with increasing Ca2+ concentration. The degree of helical ordering of the myosin heads decreased by the same amount in WT and D65A myocardium when Ca2+ concentration increased. These results are consistent with a direct effect of Ca2+ in activating the thick filament rather than an indirect effect due to Ca2+-mediated crosstalk between the thick and thin filaments.
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